Manufacture of quad cables



Oct. 18, 1966 l. EYRAUD ETAL 3,279,031

I MANUFACTURE OF QUAD CABLES Filed Nov. 26. 1965; 5 Sheets-Sheet 1 1 Insulating Tape 14 Sgnfhziic Material Cor-e 12 Metallic conducta- 15 Fibar Glass Cord.

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MANUFACTURE OF QUAD CABLES Filed Nov. 26. 1963 5 Sheets-Sheet 5 mlvflvralfi Iva/v A R/imp Mime/c6 06401046 United States Patent 3,279,031 MANUFACTURE OF QUAD CABLES Ivan Eyraud and Maurice Delorme, both of Lyon, France, assignors to Compagnie Generale dElectricite, Paris, France Filed Nov. 26, 1963, Ser. No. 327,170 Claims priority, application France, Nov. 27, 1962, 916,784 19 Claims. (Cl. 29-33) The object of the present invention is a new quad cable of the star type, intended for the high frequencies in particular.

The object of this invention is also a device for the continuous manufacture of the new quad cable.

It is known that the crosstalk between the two actual circuits of a telephone star-quad cable is primarily dependent upon the geometry of the quad. If the four condue-tors forming the quad are, on their whole length, arranged at the vertices of a perfect square, the capacity unbalances and magnetic couplings will be nil. If the conductors are identical and the insulation homogeneous, the crosstalk will be very weak between the two actual circuits of the quad which, consequently, can be used for high frequency carrier currents.

The qualities of the quad must be the following:

(1) Total relative rigidity.

(2) Lightness.

(3) Homogeneous insulating core.

(4) Precise and regular positioning of the conductors; the distance between the conductors must be strictly constant.

(5) Since the conductors are helically twisted, it must be possible to adjust the pitch, according to requirements.

The raw materials, labour and tooling used, significantly affect the cost of the quads. It is therefore advantageous to manufacture the quads from raw materials with mechanical and electrical characteristics comparatively constant under the mean conditions of utilization, which are inexpensive and can be easily processed.

To lower the labour cost, the manufacture of the quads must be carried out, as far as possible, in a continuous single operation.

The continuous manufacture requires specially constructed equipment; and it is advantageous to be able to adapt to this end, existing machinery used for the manufacture of other cables.

Various cable structures have been proposed, but none has been capable to fulfil the above mentioned conditions as a whole. In particular, we know quads comprising an insulating core in the surface of which slots are milled; the conductors are placed in the slots, the insulating core is twisted so that the conductors form a helix. In order to hold this twist, a thermosetting material is injected in the slots, the assembly being sheathed with the conventional means such as armourings, metal sheathings, etc.

Such quads do not fulfil the necessary conditions, specially by the fact that the torsion cannot be adjusted in order to bring about the desired pitch with precision. In the same way, any bending of the quad would affect the torsion of the centre core.

The object of the present invention is a quad which meets the greatest number of conditions required by the utilization of this type of cables. Another object of the invention is a manufacturing device for such a quad.

The quad as described in the present invention consists of a core formed by an insulating material stern internally reinformed by a glass fiber cord and incorporating helical grooves precisely milled on its surface, so that the conductors which are imbedded in it may be arranged,

Patented Oct. 18, 1966 in any cross section at the vertices of a square; then, the assembly can be bound with one or more insulating tapes and sheathed with means such as armours, metal sheaths, etc.

The utilization of a glass fiber cord increases the mechanical strength of the device, particularly the resistance to lengthening, when pulling during the manufacture, while the flexibility and the lightness are preserved allowing the device to be performed.

It should be noted as important that the insulating material must be resistant enough to allow a correct and accurate milling of the grooves as it is specified in the present invention. It is impossible to practice to get sufiicient accuracy by extrusion. The conductors can be laid down directly in the grooves made in such manner by a single operation without being insulated.

Thus, the conductors are supported by the stem at each point of the cable along its length instead of being held apart from place to place by distinct spreading disks as in conventional quads.

The object of this invention is also a device which allows the continuous single operation manufacture of such a quad. This device can be mounted on an existing machine or be the object of a special design.

The device as described in the present invention comprises a plate which supports a set of four electrically driven precision spindles carrying slot cutters whose active surfaces are oriented in order to cut four grooves arranged at the four corners of a square in the surface of an insulating stem which is moving forward and passing through a guide fitted at the centre of the said plate.

In the present specification, the device of the invention is described in combination with a cage type cable spinning machine; but it is clear that the limits of the invention are not exceeded if the device is mounted on any other existing cable machine or any known machine modified for the particular combination of this invention.

Other characteristics and advantages of the invention will be indicated in the description given below.

The invention will be clearly understood by referring to the attached drawings which are illustrative and not limitative and which show:

FIGURE 1, a cross section of a quad as described in the invention,

FIGURE 2, a view of a piece of cable showing clearly the helical shape of the grooves,

FIGURE 3, a longitudinal section of the manufacturing device for the quad,

FIGURE 4, an upper view of the cutter head, showing clearly the arrangement of the cutters,

FIGURE 5, an elevation view of a sector of the cutter head fitted with one of the mills, and

FIGURE 6, an upper view of a sector of the cutter head provided with one of the mills.

In FIGURE 1, the quad is formed by four conductors 12 arranged at the vertices of a square; the conductors are embedded in a core formed by an insulating material stem 14. The stem is internally reinforced by a glass fiber cord 15, this cord having a resistance to elongation much higher than that of the material stem.

Grooves 27 containing conductors 12 are obtained by milling the circular section stem 14.

The grooves are helically milled in the surface of the stern (FIGURE 2), the distance between the grooves being strictly the same at any point.

The depth of grooves 27 roughly corresponds to the diameter of conductors 12, in order not to alter too much the cylindrical structure of the assembly. The obtained quad can be bound with one or more insulating tapes as shown by the reference numeral 16. It is then coated with an insulating plastic material sheath, and covered with any of the conventional means used for the protection of the telephone cables, such as screen, metal sheathing, etc.

The four grooves 27 are simultaneously machined by means of adequately shaped slot cutters carried by four milling sets which can be precisely adjusted.

In order to minimize any systematic defect resulting from an asymmetry of the four milling sets and to allow for the inevitably limited precision of the adjustments, the grooves are subjected, at regular intervals, to a circular permutation in relation to the cutters.

This circular permutation will be advantageously carried out by rotating the drilling device through an angle of 90, the stem being preferably immobilized so that the groove drilled by one of the cutters willbe in the lengthening of the groove drilled by a second cutter substituted for the first cutter. Thus each groove will have the form of a continuous helix, the stem having periodically a circular groove due to the rotation of the drilling device as it will be seen more clearly in the course of the detailed description of functioning of the drilling device.

It is understood that any other permutation method can be choosen in order to improve the precision regarding the positioning of the grooves, for example, a series of permutations of 90, 180, 90", 180 and 90 may give the wanted compensation of the defects.

For instance, in the case of a circular permutation, if L is the length chosen between two successive permutations, the completed quad will have a length multiple of 4L.

The device for the manufacture of the cable concerned is shown in FIGURES 3, 4, 5, 6, as an example. The below described device has been fitted on a cage type cable spinning machine. It can be mounted in any suitable machine or to be the object of a special design.

The cable spinning machine provided with the device as described in the present invention is shown longitudinal section, in FIGURE 3.

Stem 14 introduced in cylinder 29 is guided by device 30 carrying dogs 9 which can stop the longitudinal motion of the stem.

A second guide 3 ensures the guidage of the stem during the milling, this guide comprising, in addition, four oblique slots which allow the passage of cutters 18. The stem then passes through a suction chamber 10 connected to cylinder 29 by a duct 24 ending in a revolving joint 31. The suction chamber is integral with a ring 5.

Rotary brushes 11 are then arranged around the stem.

The cage of the cable spinning machine is formed by plates 32, 33, 34, 35, free to rotate around an axis parallel to the axis of stem 14.

This cage is driven by a device not shown in the figure.

The cage comprises coils 41 of conductors 12; the conductors are led, by means of a system of pulleys, to the cabling point where a die. 13 ensures their positioning in the grooves milled in stem 14.

A plate 1 together with the devices it supports can rotate around the axis of the cage, through rollers 4 inside a roller-ring secured to the cage of the cable spinning machine.

A mooring finger 6 permits the locking of the said ring with plate 1.

The motors arranged on plate 1 are supplied with power through slip-rings 7 and brushes 8. The slip-rings are. placed on a hollow cylinder 36, integral with ring 5.

A ball bearing 37 is interposed between plate 1 and device 30 which is secured to hollow cylinder 36.

Plate 1 which represents one of the characteristics of the device as described in the invention is shown in FIG- URE 4, in projection on a planperpendicular to the rotation axis.

FIGURE 4 shows clearly the arrangement of the four milling sets 2: cutters 18 are carried by spindles 17 driven by electric motor 19.

This device allows the milling. of grooves 27 which are arranged substantially at the four vertices of a square.

In order to ensure the desired symmetry, a circular permutation of the cutters is periodically carried out by rotating plate 1 in relation to ring 5 integral with the cage, by

FIGURE 5 is an elevation view of one of the four milling sets arranged on plate 1. Convex shaped cutter 18 is borne by a precision spindle 17 which is driven by an electric motor 19.

The spindle and the motor are secured to a carriage 20 movable longitudinally to the direction of the spindle.

Carriage 20 is itself supported by a second carriage 21, movable transversally to the direction of spindle 17.

Both carriages 20 and 21 are moved by the action of micrometric screws '22 and are held by means of a tie, brace or strut (lardon) and a screw lock, not shown in the figure.

Transversal carriage 21 can rotate around a pivot 23. The angle of the spindle in relation to the plate can he therefore adjusted owing to a toothed quadrant 38 and a tangent screw 39.

FIGURE 6 is an upper view of a sector of the plate provided with one of the mills already shown in elevation, in FIGURE 5.

The processing and assembling device for the quads is above described only as an example of carrying out, in order to'understand better the invention. Many alternatives can be used without going beyond the limits of the invention, specially as regard the arrangement of the adjusting elements of the cutter and the control of the cutter head rotation, the arrangement of secondary elements such as the brushes, the chip suction systems. So it is with the shape of the assembling cage, since the cutter head as described in this invention can be used jointly with a large number of types of cages generally used in the cable spinning industries.

The operation of the manufacturing device for the quads is the following:

Plate 1 being made integral with ring 5 by finger 6 is rotated by the cage of the spinner. The material stem, accurately calibrated, is drawn by a capstan (not illustrated in the figures) and passes through the hollow cylinder, dog 9 which is open.

At the level of guide 3 the cutters, which have been precisely adjusted, dig the four helical grooves. The chips are sucked at the suction chamber 10 that ensures a coarse cleaning of the grooves, cleaning which is completed by rotating brushes 11. Copper wires 12, delivered by the coils carried by the cage, are brought to the point of wiring, where a die 13 ensures their positioning in the grooves. Then, one or more insulating tapes can be placed by a taping head before passage on the capstan and reception at the spinning wheel. The wiring pitch is given by the combination of the forward movement of the stem and the rotation of the cage. The angle of the cutters in relation to the longitudinal axis of the stem is adjusted according to this pitch.

To perform a permutation of the grooves in relation to the cutters, the procedure is the following:

The pulling of the stem and the rotation of the cage-are stopped when the desired exact length has been reached. The cutters are let in operation. Dog 9 is closed, holding the stem. Finger 6 is pulled; plate 1 free is made to rotate by 90. The permutation of the grooves is thus carried out. The circular gorge dug in the stem by the cutters working with their side surfaces, facilitates the passage of the wires from a groove to the groove which is milled in its lengthening'by the new cutter. Finger 6 is then engaged in a new bedding and makes platel integral with ring 5; dog 9 is open and the machine is normally restarted.

As it has been said before, the quad manufactured in this'way is subsequently sheathed with an insulating layer, then, according to the case, with a screen, a metal sheathing, an armour, etc.

In addition to the electrical qualities already mentioned and which are dependent upon the precision of milling of the grooves, this type of cable shows the mechanical qualities peculiar to the quad, i.e. lightness and flexibility. As indicated in the preambule, this new quad can be used with high frequency currents. The utilization for carrier currents authorizing a large number of communication channels is therefore possible.

In addition, the quad as described in the present invention can be manufactured very easily. It is not necessary to secure the conductor in the groove milled in the centre core, since this groove is machined with a great precision according to the dimensions of said conductor. In the same way, no torsion is applied to the core, since the groove has already the desired helical shape.

The device as described in the present invention can be readily adapted to most of the cage type cable spinning machines; consequently, the cost of the required machines is comparatively low. So it is with the cost of the cable which can be manufactured continuously and semiautomatically without intermediary operations, by using a new material particularly easy to process.

We claim:

1. An apparatus for continuous manufacture of a cable having a core and a plurality of electrical conductors comprising:

means for continuously supplying a core,

means for drilling a plurality of grooves in the outer surface of said core, including a supporting means, including means accommodating the passage of the core therethrough, for supporting a plurality of electrically driven precision spindles carrying cutter means for drilling a plurality of grooves in the outer surface of the core, said grooves being positioned at the corners of a regular polygon, said supporting means being mounted rotatably about the axis of the core such that each cutter is substituted for another cutter in its position upon rotation of said supporting means, and means for posltromng electric conductors in said grooves.

2. An apparatus according to claim 1, wherein said means for drilling the grooves and said means for posi tioning the conductors in the grooves are both mounted rotatably about the axis of the core.

3. An apparatus according to claim 2, comprising driving means operatively connected with said means for positioning the conductors and said means for drilling the grooves for eifecting rotation thereof at the same speed.

4. Apparatus according to claim 1, wherein said means for allowing the passage of the core through said supporting means comprises stop means for stopping the longitudinal movement of the core through said supporting means.

5. Apparatus according to claim 1, wherein said plurality of spindles consist in four spindles carrying cutters operable to drill four grooves positioned respectively at the corners of a square.

6. Apparatus according to claim 1, wherein said supplying means are operable to continuously supply an insulating core having a circular cross section.

7. Apparatus according to claim 1 comprising means for aspirating the chips produced by drilling the grooves in the core.

8. Apparatus according to claim 7, wherein said means for aspirating the chips comprise a Venturi tube.

9. Apparatus according to claim 1 comprising brush means operable to remove the chips produced by drilling the grooves in the core.

10. Apparatus according to claim 2, wherein said sup porting means is mounted free in rotation about cylindrical member mounted rotatable about the axis of the core, said cylindrical member being secured to said positioning means so as to be driven by said positioning means in rotation about a common axis, said supporting means being secured to said positioning means by way of removable fingers.

11. Apparatus according to claim 10, wherein said supporting means is mounted on said cylindrical member by means of a ball bearing.

12. Apparatus according to claim 2, wherein said supporting means comprises rollers engaging a roller ring secured to said positioning means mounted rotatably about the axis of the core, said supporting means thus being mounted free in rotation about the same axis, said supporting means further comprising removable fingers engaging said' roller ring for securing the supporting means thereto.

13. Apparatus according to claim 1, wherein said cutters are convex.

14. Apparatus according to claim 1 comprising separate electrical motors for driving each spindle and adjustable securing means for securing said motors to said supporting means, said securing means being operable to adjust the position of the spindle along a line parallel to the direction of this spindle.

15. Apparatus according to claim 14, wherein said securing means are further operable to adjust the position of the spindle along a line perpendicular to the direction of this spindle.

16. Apparatus according to claim 15, wherein said securing means comprises adjusting means for precise adjustment of the position of the assembly of each spindle and its driving motor.

17. Apparatus according to claim 14, comprising means for rotating said securing means about an axis parallel to the axis of the core.

18. Apparatus according to claim 1, wherein said means for positioning the conductors in the grooves is a cage-type cable spinning machine.

19. An apparatus for continuous manufacture of a cable including conductors positioned in grooves provided in a core the relative position of said grooves being exactly and periodically repeated along the length of the core, comprising:

means for continuously supplying a core having a circular section and at least an outer layer made of synthetic material,

means for drilling four grooves in the outer surface of said core, said grooves being positioned at the corners of a square, comprising a supporting member, mounted in said apparatus, having means for allowing the passage of the core therethrough, mounted rotatably about the axis of said core and supporting four spindles carrying cutters and four electric motors for driving said spindles,

means for positioning electric conductors within said grooves, including a cage having means for allowing the passage of the core therethrough and mounted rotatable about the axis of said core, and removable locking means, connected with said cage and said supporting means for securing each to another, said lock ng means being operable to drive said supporting member about said axis upon rotation of said cage, said supporting member being further 0perable to rotate about the same axis and relative to said cage upon removal of said locking means, in such a manner that each cutter is substituted for another cutter in its position.

References Cited by the Examiner UNITED STATES PATENTS 716,155 12/1902 West 174-27 1,751,549 3/1930 Hope et al. 835 2,234,435 3/1941 Johnson 174-27 2,677,313 5/1954 Biegert 835 RICHARD H. EANES, JR., Primary Examiner. DARRELL L. CLAY, Examiner. D. A. KETTLE-STRINGS, Assistant Examiner. 

1. AN APPARATUS FOR CONTINUOUS MANUFACTURE OF A CABLE HAVING A CORE AND A PLURALITY OF ELECTRICAL CONDUCTORS COMPRISING: MEANS FOR CONTINUOUSLY SUPPLYING A CORE, MEANS FOR DRILLING A PLURALITY OF GROOVES IN THE OUTER SURFACE OF SAID CORE, INCLUDING A SUPPORTING MEANS, INCLUDING MEANS ACCOMMODATING THE PASSAGE OF THE CORE THERETHROUGH, FOR SUPPORTING A PLURALITY OF ELECTRICALLY DRIVEN PRECISION SPINDLES CARRYING CUTTER MEANS FOR DRILLING A PLURALITY OF GROOVES IN THE OUTER SURFACE OF THE CORE, SAID GROOVES BEING POSITIONED AT THE CORNERS OF A REGULAR POLYGON, SAID SUPPORTING MEANS BEING MOUNTED ROTATABLY ABOUT THE AXIS OF THE CORE SUCH THAT EACH CUTTER IS SUBSTITUTED FOR ANOTHER CUTTER IN ITS POSITION UPON ROTATION OF SAID SUPPORTING MEANS, AND MEANS FOR POSITIONING ELECTRIC CONDUCTORS IN SAID GROOVES. 